1. Field of the Invention
The present invention relates generally to modem adapters. More specifically, the present invention relates to a universal adapter for a modem, such as a PSTN modem, that allows for modem connectivity over a variety of telephone systems.
2. Background of the Invention
Computers manufactured for use in North America, and the communications programs that are intended to operate on these computers, typically expect certain line conditions for proper operation, for example, line voltage, presence of a physical RJ11 connection, dial tone, etc. In some locations both inside and outside of North America, some of these conditions may not be present. This can result in faulty operation, including complete failure, of computer modems.
In most North American countries, the PSTN connection is made via the inner two conductors on an RJ11 jack. Outside of these countries, this connection may be made via the outer two conductors. In this scenario no physical connection would be made between the computer modem and the actual PSTN connection.
Another problem arises from differences in dial tones. The dial tone cadence in some countries can be different enough from what is expected by the computer that the modem fails to detect the dial tone or may even incorrectly interpret the dial tone as a busy tone, among other problems. In either of these cases, or other similar situations whereby the modem is confused by an unfamiliar dial tone, the modem will not dial.
Some modems also require detection of line voltage within a certain range in order to qualify that the line condition is appropriate for dialing. Central office switches in countries outside North America may or may not confirm these requirements. Such discrepancies between North American and other countries can cause modem failure.
In many cases, computers used in hotels suffer from similar problems. A computer used at a hotel will often access a PSTN connection through a PBX, which can affect the dial tone cadence and line voltage. Either of these conditions can cause the modem to fail.
To overcome some of these problems various solutions have been attempted. For example, certain hardware is available that allows connectivity between different kinds of telephone jacks. These adapters, however, do not sense which of the conductors are “live,” nor do they switch the inner pair for the outer pair as may be required.
Software solutions have also been tried. For example, some communications programs allow for disabling of some of the dialing safeguards such as dial tone detection. This solution often results in inconsistent operation and may be difficult to locate within the program. Often times, even with such a solution in place, users do not have the requisite computer skills to implement the necessary software changes, resulting in poor modem performance.